1. Field of the Invention
This invention relates to refrigeration equipment for use in applications where a probe is placed within an environment to remove heat therefrom. More particularly, the invention relates to the configuration of a remote refrigeration probe. The invention concerns the structure of the probe and how a refrigerant is conducted through the probe to provide a refrigerative effect.
2. Description of Related Art
Refrigerative probes can be useful in certain applications, for example, harsh chemical environments, high humidity, wet, or liquid environments where it is convenient to often place the probe in and out of the environment, for example for cleaning. It has been found for example that such probes are very useful for controlling the temperature of aquariums where the desired temperature of the liquid environment within the aquarium is below the ambient temperature of the environment surrounding the aquarium.
Also, remote refrigerative probes are useful and convenient when portability or manipulation of a cooling probe may be useful or required. For example in a manufacturing environment, or chemical processes it may be advantageous to easily move a cooling probe from one place or environment to another. Also, for example, in certain medical applications, including surgery, manipulation of a cooling probe would be desirable.
Refrigerative probes are also useful in refrigeration applications where size constraints are important; particularly concerning diameter of a refrigerative device that is invasive. For example, in the past refrigerative probes have been used to more rapidly freeze the interior of animal carcasses, to better preserve meat. In another example, thermal stabilization of soil has been undertaken using remote refrigeration techniques. This application usually requires that heat be evacuated through bore holes, hence refrigeration probes can be particularly useful.
Prior art refrigerative probes have a number of drawbacks. First, certain prior art probes having a relatively small size or cross-section are of relatively inefficient design. In such probes a central refrigerant tube extends through the interior of an outer probe housing to nearly reach a distal end. Refrigerant transits the tube and doubles back through the probe in a luminal space between the inner tubing and the outer probe housing. That arrangement is simple and low cost, however, it is relatively inefficient for heat transfer, as the refrigerant is in contact with the probe for only a very short time. The refrigerant optimally should be in contact with the probe for a prolonged period of time to absorb heat and more efficiently conduct heat from the environment of the probe away through an umbilical.
The efficiency of prior art refrigerative probes has been increased by the provision of coiled probes or of coils within the probe, whereby refrigerant is made to dwell longer within the probe for increased heat transfer. Such devices still have a number of problems however. Probes which comprise a coiled tube, or have a tubing coil on the external surfaces thereof may be more susceptible to damage by dents or otherwise fragile, or difficult to clean. Further, they may be more prone to problems in corrosive environments due to this cleaning problem. If a coil is contained within a separate protective housing, heat transfer between the environment and the coil may be compromised to some extent as heat then must be conducted through the housing as well as the coil, as well as any medium contained within the probe as to the majority of the surface area of the coil which is not in contact with the housing.
Additionally, provision of more complex arrangements (including spiral tubing arrangements) may contribute to higher cost in manufacturing refrigerative probes, due to an increased difficulty of manufacture.
Prior refrigerative probes with complex configurations, including spiral tubing arrangements and other complex geometries for increasing the thermal transfer efficiency properties of the probe may be difficult to miniaturize. Therefore the size of such devices is limited to relatively larger configurations making them unsuitable for certain applications. Moreover, the more complex and/or efficient the refrigerative probe is, the more resources must be applied in its manufacture, increasing its cost.
Hence, those concerned with the development and use of remote refrigerative probes have long recognized the need for an improved probe which will enable low cost manufacture of the device and yet give the relatively higher efficiencies associated with more complex devices. It has also been recognized that it would be desirable to obtain these properties in a probe that is rugged and adapted for use in harsh conditions, or environments where cleanliness is at a premium. The present invention fulfills these needs.